Sharps often gets asked which upper matches the best with Sharps receivers. Any mil-spec upper will work, that is the beauty of the platform ... but which one fits and matches the best? The answer is this one. The SBUR03 matches all of Sharps lower receivers perfectly, but it also matches the lines of Sharps hand guards perfectly as well. This receiver is meant for .223, 5.56, .224 Valkyrie, 300 BLK and 6.5 Grendel calibers. Port opening is not large enough for 450 Bushmaster, 458 SOCOM or 50 Beowulf. Made from 7075-T6 just like Sharps lower receivers. Anodized black. Comes with forward assist kit & dust cover installed.